Fuel metering device



Nov. 22, 1966 J. D. SMITH 3,286,491

FUEL METERING DEVICE Filed April 27, 1964 United States Patent M3,286,491 FUEL METERING DEVICE James D. Smith, Stroudsburg, Pa.,assignor to Ronson Corporation, Woodbridge, N.J., a corporation of NewJerse y Filed Apr. 27, 1964, Ser. No. 362,727

7 Claims. (Cl. 67--7.1)

This invention relates to fuel metering devices of a type suitable forusewith gas fueled cigar lighters.

In gas lighters, wherein highly volatile fuel is maintained in liquidform under pressure in the lighter fuel tank, it is necessary to providea fuel metering means such that a controlled but complete evaporation ofthe fuelwill take place. prior to its being emitted from the burnernozzle of the lighter. This is done, in some cases, by means of asintered. pellet located in a passageway leading from the lighter fueltank to the burner nozzle. The porosity of these pellets is such as toprevent the flow of liquid through them; but is sufficient to permitevaporated fuel in the gaseous state to pass out of the fuel containerand through the burner nozzle. There is also generally provided afibrous wick which extends downwardly from the pellet to a point belowthe liquid surface of the fuel contained within the lighter. The liquidfuel is transmitted through the wick by capillary action and wets thebottom of the pellet. This insures that evaporation of the fuel willtake place within the pellet itself, thereby promoting a more even andcontrollable flow of fuel at the burner nozzle.

According to one feature of the present invention there is provided aporous type fuel metering device wherein evaporation takes place with aporous element and yet no wick is required to convey theliquid fuel tothe element. Thus, in the present invention the problemjof securing awick in proper position relative to the fuel tank and the porouselement, is eliminated. Also eliminated is the problem of insuring thatthe wick 18 maintained inintimate contact with the porous materialcomprising the element so as to permit transfer of the fueltherebetween.

According to a further feature of the present invention, the overallstructure of a fuel meteringassembly is considerably simplified. Thishasbeen accomplished through the provision of a porous element of aparticular size, shape and porosity as well as the provision of a uniquemeans for supporting the porous element w1th1n the fuel container. Morespecifically, in the present invention an elongated porous elementextends between the lighter burner nozzle and a point near the bottom ofthe fuel container. The porosity of this element is such as to ermit ahighly restricted but nevertheless, positlve flow of fuel in its liquidstate through the, element. Means are also provided for preventing anyfluid flow, either liquid or gas, through the sides of the meteringelement. Thus, all fuel flowing through the element must proceed alongits entire length. Means may additionally be provided above the porouselement for adjusting the volume rate of flow of gaseous fuel or forclosing off the flow of fuel entirely.

There has thus been outlined rather broadly the more important featuresof the invention in order that the detailed description thereof thatfollows may be better understood, and in order that the presentcontribution to the art may be better appreciated. There are, of course,additional featuresof the invention that will be described hereinafterand which will form the subject of the claims appended hereto. Thoseskilled in the art will appreciate that the conception upon which thisdisclosure is based may readily be utilized as a basis for the designingof other structures for carrying out the several pur- 3,286,491 PatentedNov. 22, 1966 poses of the invention. It is important, therefore, thatthe claims be regarded as including such equivalent constructions as donot depart from the spirit and scope of the invention.

A specific embodiment of the invention has been chosen for purposes ofillustration and description, and is shown in the accompanying drawings,forming a part of the specification, wherein:

FIG. 1 is a side elevation, partially in section of a lighter embodyingthe present invention;

FIG. 2 is a section view taken through line 22 of FIG. 1;

FIG. 3 is a section view taken through line 33 of FIG. 2.

The lighter shown in FIG. 1 comprises a body portion 10 having ahorizontal top wall 12 which supports a burner nozzle 14, a sparkingwheel 16 and a flint tube 18 in operative positional relationship toeachother. A closure cap 20 covers the operative components of the lighterwhen the lighter is not being used.

The body portion 10 is hollow and has formed therein a fuel container 22which is tightly sealed to maintain highly volatile fuel such as butanein its liquid form above atmospheric pressure. Because of the pronouncedtemperature sensitivity of most such fuels, whereby in their liquidstate they undergo great changes in volume in response to even moderatetemperature changes, such lighters are filled only to a given point suchthat a cushion of vapor 24 is maintained above the maximum liquid levelof the fuel within the lighter. This allows the liquid fuel to expandwith changes in ambient temperature, the expansion being absorbed by thecushioning effects of the vapor within the fuel container. The amount ofspace allotted to the vapor cushion 24 of course is determined.according to the construction of the fuel container 22 and thetemperature characteristics of the fuel, commensurate with acceptedstandards of safety.

The burner nozzle 14 rests upon an adjustable valve element 26. Theadjustable valve element in turn operatively engages a valve housing 28which protrudes through the top wall 12 from within the fuel container22. The valve housing 28 is sealed to the horizontal top wall to preventleakage of fuel from the container. It extends downwardly Within thecontainer to a point near its bottom.

The construction of the valve housing 28, the adjustable valve element26 and their operative relationship to each other is best shown in FIG.2. The valve housing 28 is of generally tubular construction and is openat both ends. The lower portion of the valve housing 28 encases a porouselement 30. The material comprising this element is characterized by amyriad of minute interconnected tortuous passageways of a size whichpermits restricted but positive flow of liquids and relatively free flowof gases through the material. Preferred forms of such material includepressed and sintered granules of some plastic such as nylon or Teflon,or of some metallic oxide such as iron oxide. Certain porous ceramicsalso may be used for this purpose. It is essential however that thematerial be of relatively uniform density and thatthe passagewayscontained therein are of a proper size. Also the material itself mustnot be chemically reactive to the fuel used by the lighter.

The valve housing 28 is provided with a cylindrically shaped fuelpassageway 32 immediately above the porous element 30. The cylindricalpassageway 32 is of much smaller cross-sectional area than is the porouselement 30 for reasons to be explained herein.

The adjustable valve element 26 is threadedly engaged in the valvehousing 28 just above the cylindrical passageway 32. A conically shapedprotrusion 34 is located centrally of the element and extends into thecylindrical passageway 32 of the valve housing 28. By turning theadjustable valve element 26, the conically shaped protrusion 34 is movedlongitudinally into or out of the cylindrical passageway 32 thus varyingits effective area. This in turn controls the volume rate of flow offuel through the valve housing. The adjustable valve element 26 includesan internal passageway 36 (shownin dotted lines) which extends betweenthe burner nozzle 14 and the lower portion of the adjustable valveelement 26 in communication with the cylindrical passageway 32. There isthus provided a complete connection for fluid passage from a point nearthe bottom of the container 22 up through the valve housing 28 and theadjustable valve element 26 to the burner nozzle 14. The adjustablevalve element 26 is also provided with an upper peripherally knurledportion 38 which permits convenient manual adjustment for changing thevolume rate of fuel being emitted from the burner nozzle. An O-ring 40or similar resilient seal is provided between the adjustable valveelement 26 and the upper portion of the valve housing 28 in order toprevent undesired leakage of fuel from between the threaded regions ofthese elements.

Because of the fact that the valve housing 28 extends to a point nearthe bottom of the fuel container 22, the porous element 30 is alwaysmaintained in contact with the liquid fuel even though no fibrous wickas such is provided. Furthermore, because of the fact that the porouselement 30 is surrounded by the fluid impermeable sides of the valvehousing 28, none of the vapor from the vapor cushion 24 above the liquidlevel of the fuel can short circuit through the side of the porouselement 30 to the burner nozzle 14. This insures that all of the fuelwhich reaches the burner nozzle passes through the entire length of theporous element 30 and is evaporated therein. Thus smooth and efficientflow of fuel as well as complete flame control is always presentregardless of the liquid level within the fuel container.

It is important in carrying out the present invention that the porouselement 30 extend continuously from a point near the bottom of the fuelcontainer to a point above the liquid level in the fuel container whichis not wetted by the capillary effects of the porous material on thefuel. This is necessary in order to prevent liquid fuel from graduallybeing drawn up into the cylindrical passageway 32 when the lighter isnot in use. Such a situation would result in dangerous flaring when thelighter is operated. The minimum amount by which the porous elementshould extend above the liquid level depends of course upon the densityof the liquid fuel, its surface tension characteristics and the size andcondition of the openings within the porous element 30. In most cases,however, it need not extend significantly above the top of thecontainer. When the fuel container is freshly charged the liquid fuelreaches a maximum level well below the top of the container in order toprovide space for the vapor cushion 24. In most cases this distance ismore than adequate to overcome the capillary effects within the porousmaterial comprising the element 30.

It is to be noted that as the lighter is used and the liquid level inthe fuel recedes, the liquid level in the porous element 30correspondingly recedes. However, in spite of this, flame height andcontrollability are negligibly affected. Even though the evaporationprocess takes place further and further toward the bottom of the porouselement 30 as the fuel in the container is consumed, the vapors producedby the evaporation are of negligible viscosity compared to that of theliquid fuel. They thus pass through the porous material with ease andare substantially unaffected by its length.

Because the cross-sectional area of the porous element 30 is largecompared to that of the cylindrical passageway 32, liquid fuel can beabsorbed into the bottom of the material at a greater rate than gaseousfuel is emitted through the passageway. This helps to insure thatevaporation takes place well within the porous element and not at itslower surface. A further advantage of the large cross-sectional area ofthe porous material lies in the increased liquid fuel storage capacitythus afforded. Because of this there is always a supply of liquid fuelsufficient for at least one normal operation regardless of the fact thatfuel in the container 22 may be at a very low level and that the lighteritself may be tilted or even inverted during use.

It should be noted that there are certain dimensional and other relatedstructural limitations which must govern the particular porous element.It is important, for example, to maintain a substantially constant flameheight as the quantity of fuel in the lighter fuel container decreases.Thus it is necessary that the quantity or rate of fuel emission be keptconstant. Since the porous element extends down to near the bottom ofthe lighter fuel container, evaporation will take place, allowing forcapillary effects, at a point slightly above the liquid level in thefuel container. The porosity of the porous element should be high enoughso that the viscosity of the evaporated fuel will have negligible effectin retarding its flow through the element no matter at which levelevaporation takes place. On the other hand, it is important that theporosity of the element, as well as its height above the highest liquidlevel of the fuel container, be such as to prevent non-evaporated fuelfrom being emitted.

The rate of fuel flow out of the porous element can be expressed asfollows:

where It will be noted that as the liquid level in the lighter fuelcontainer decreases, the distance L through which the fuel must travelcorrespondingly increases, thus tending to reduce fuel flow rate andflame height. The effect produced by this length, however, is rathersmall for vapors because of the extremely small K values which theypossess. Further, by increasing the porosity P to its maximumpermissible amount the length effect can be reduced even moresignificantly.

The amount by which the porosity can be increased, however, is limitedby its ability to prevent fuel in its liquid state from flowingcompletely through the porous element. Thus when the lighter fuelcontainer is filled the porous element must extend above the liquidlevel by a distance 1, sufficient to ensure that no liquid passes outthrough the top of the element. The relation between this distance andthe porosity of the element can be expressed as follows:

where K =a constant governed by the density and viscosity of the fuel inits liquid state.

The maximum porosity P, for a given fuel, is limited by the distance 1,which in turn is governed by the practical dimensional limitations ofthe lighter. This maximum porosity in turn governs the necessarycross-sectional area which the porous element must possess to obtain agiven maximum fuel flow rate with a minimum of variation due to adecreasing amount of fuel in the lighter fuel container.

The cross-sectional view of the lower portion of the valve housing 28shown in FIG. 3 indicates the preferred configuration of this element tobe rectangular or square in shape. The purpose for this is to afford amore closely controlled manufacture of the porous element 30 containedwithin the housing when the porous element is made by compression andsintering. Most granulated particles, when subjected to compression inconnection with sintering, exhibit a high degree of friction relative toone another. This causes an unevenness in applied pressures particularlywhen the source of pressure is far removed from certain points withinthe sintered material. For this reason it is preferred to compress thiselongated element laterally rather than longitudinally as is theconventional practice. By applying lateral pressure no portion of thesintered material is far removed from the pressure source and therebyachieves an ultimate density commensurate with the average densitythroughout the element. It has also been found that rectangular orsquare shapes are better suited to lateral compression in that theyrespond more evenly to the forces imparted during such compression thando cylindrical or rounded shapes.

Having thus described my invention with particular reference to thepreferred form thereof, it will be obvious to those skilled in the artto which the invention pertains, after understanding my invention, thatvarious changes and modifications may be made therein without departingfrom the spirit and scope of my invention, as defined by the claimsappended thereto.

What is claimed as new and desired to be secured by Letters Patent is:

1. An improved lighter comprising, a fuel container capable of holdinghighly volatile fuel in its liquid state above atmospheric pressure, aburner nozzle mounted above said fuel tank for directing the flow ofgaseous fuel from said tank, a passageway interconnecting said fuelcontainer and said burner nozzle, an elongated porous element containingtherethrough a myriad of tortuous interconnected passageways of a sizesufficient to permit restricted but positive flow of liquids and freeflow of gases, said elongated porous element mounted to extend from alower point within said casing near its bottom to an upper point withinsaid tubular passageway located sufficiently above the maximum liquidlevel capacity of said container to prevent capillary Wetting of saidporous element above said upper point, said elongated porous elementfurther being provided over its entire length with a fluid imperviouslateral surface which is tightly sealed to said tubular passageway.

2. The lighter described in claim 1 wherein said porous element is asintered mass of granules of preselected size compressed to apredetermined density, said granules being chemically inert to lighterfuels.

3. The lighter described in claim 2 wherein said porous element is ofrectangular cross-sectional configuration and is pressed laterally touniform density.

4. An improved lighter comprising, a pressurized fuel containercharacterized by a maximum liquid fuel level commensurate with acceptedstandards of safety, a burner nozzle mounted above said fuel tank fordirecting the flow of gaseous fuel from said tank to a flame at theoutlet of said burner nozzle, an elongated fuel vaporizing elementlocated between said fuel container and said burner nozzle, said fuelvaporizing element including a myriad of interconnected tortuous fluidpassageways which extend from a lower point within said fuel containernear its bottom to an upper point located above said maximum liquid fuellevel by an amount greater than the maximum capillary effect producibleby said passageways upon liquid lighter fuel, and fluid impervious meanslaterally surrounding said fuel vaporizing element over its entirelength, but permitting contact between the lowermost surface of saidfuel vaporizing element and liquid fuel within said container.

5. An improved lighter comprising, a fuel container capable of holdinghighly volatile fuel in its liquid state above atmospheric pressure, anelongated tubular valve housing open at both ends and extending upwardlyfrom a point within said fuel container near its bottom out through itstop and sealed thereto, a porous material chemically resistant tolighter fuels and characterized by a myriad of tortuous interconnectedpassageways which permit restricted but positive flow of liquids andfree flow of gases, said porous material filling the lower portion ofsaid valve housing to a level located sufficiently above the maximumliquid level capacity of said fuel container to prevent capillarywetting thereabove, and a burner nozzle mounted above and connected tosaid valve housing.

6. The lighter described in claim 1 wherein said burner nozzle isconnected to said valve housing through a closeable cylindricalpassageway within said valve housing above said porous material, saidcylindrical passageway having a cross-sectional area considerably lessthan the cross-sectional area within the lower portion of said valvehousing.

7. The lighter described in claim 6 further including means forcontrollably varying the effective cross-sectional area of saidcylindrical passageway.

References Cited by the Examiner UNITED STATES PATENTS 2,692,492 10/1954Hepburn 677.1 2,708,842 5/1955 Nissen 677.1 2,737,037 3/1956 Zellweger67-7.1 X 3,095,175 6/1963 Iketani 67-7.1 X 3,148,522 9/1964 Court 677.1

FOREIGN PATENTS 1,187,564 3/1959 France.

EDWARD 1 M CH E im y E am ne

1. AN IMPROVED LIGHTER COMPRISING, A FUEL CONTAINER CAPABLE OF HOLDINGHIGHLY VOLATILE FUEL IN ITS LIQUID STATE ABOVE ATMOSPHERIC PRESSURE, ABURNER NOZZLE MOUNTED ABOVE SAID FUEL TANK FOR DIRECTING THE FLOW OFGASEOUS FUEL FROM SAID TANK, A PASSAGEWAY INTERCONNECTING SAID FUELCONTAINER AND SAID BURNER NOZZLE, AN ELONGATED POROUS ELEMENT CONTAININGTHERETHROUGH A MYRIAD OF TORTUOUS INTERCONNECTED PASSAGEWAYS OF A SIZESUFFICIENT TO PERMIT RESTRICTED BUT POSITIVE FLOW OF LIQUIDS AND FREEFLOW OF GASES, SAID ELONGATED POROUS ELEMENT MOUNTED TO EXTEND FROM ALOWER POINT WITHIN SAID CASING NEAR ITS BOTTOM TO AN UPPER POINT WITHINSAID TUBULAR PASSAGEWAY LOCATED SUFFICIENTLY ABOVE THE MAXIMUM LIQUIDLEVEL CAPACITY OF SAID CONTAINER TO PREVENT CAPILLARY WETTING OF SAIDPOROUS ELEMENT ABOVE SAID UPPER POINT, SAID ELONGATED POROUS ELEMENTABOVE BEING PROVIDED OVER ITS ENTIRE LENGTH WITH A FLUID IMPERVIOUSLATERAL SURFACE WHICH IS TIGHTLY SEALED TO SAID TUBULAR PASSAGEWAY.